KR20110081185A - Method and control unit for actuating a fuel injector - Google Patents

Abstract

The present invention relates to a method for driving a fuel injector of an internal combustion engine, the method comprising the following method steps. First, the driving time point of the fuel injector is determined. Then, the number of driving of the fuel injector is determined within a predetermined time interval before the driving time point, and the driving voltage of the fuel injector is determined based on the determined number of times. In yet another aspect, the present invention provides a computer program product and a control device for executing a method for driving a fuel injector of an internal combustion engine. The control apparatus includes a time determining device for determining a driving time of the fuel injector, a counter for determining the number of driving of the fuel injector within a preset time interval before the driving time, and a driving voltage of the fuel injector based on the determined number of times. It includes a voltage determiner to determine.

Description

METHOD AND CONTROL UNIT FOR ACTUATING A FUEL INJECTOR}

The present invention relates to a method for driving a fuel injector of an internal combustion engine. A computer program product for carrying out the method and a control device for driving a fuel injector of an internal combustion engine are also subject of the invention.

Modern internal combustion engines often include fuel injectors that are supplied with an electric drive signal by an appropriate control device to inject the desired amount of fuel into the intake or combustion chamber of the internal combustion engine. The electrical energy of the drive signal is converted into mechanical work, for example by an electromagnetic actuator or piezoelectric actuator inside the fuel injector.

In general, the behavior of the actuator and the behavior of the fuel injector are all influenced by the temperature of each actuator, for example, the resistance of the electromagnetic coil of the electromagnetic actuator or the material properties of the piezoelectric ceramic of the piezoelectric actuator. Because. To compensate for the effect of temperature on the injection behavior of the fuel injector, the actuator temperature can be estimated, for example, from the coolant temperature and / or the fuel inlet temperature of the internal combustion engine, and correspondingly the target drive voltage of the piezoelectric actuator, for example, at elevated temperatures. The driving signals can be dynamically matched by raising.

However, in this case, when the actuator temperature is not completely determined by the coolant temperature or the fuel inlet temperature, for example, due to frequent driving and the resulting heat introduction, the actuator temperature is much higher than the coolant temperature or the fuel inlet temperature, so that the temperature is no longer at this temperature. When it cannot be derived from these, still undesired temperature dependence of the spraying behavior may appear.

Accordingly, the present invention proposes a method of driving a fuel injector of an internal combustion engine, comprising the following steps. First, the driving time point of the fuel injector is determined. Then, the number of driving of the fuel injector is determined within a predetermined time interval before the driving time point, and the driving voltage of the fuel injector is determined based on the determined number of times.

The counting of the drives carried out during a pre-settable time period immediately before the next drive is stopped, so that the heat introduction by the drives during the time period and the resulting temperature rise of the actuator can be taken into account in the calculation of the drive voltage. Thus, the temperature dependence of the injection behavior can be compensated for even if the actuator temperature is not completely determined from the coolant temperature or the fuel inlet temperature. Only drives for a pre-settable time period are detected, such that the temperature rise caused by more preceding drives, i.e., such earlier drives, is reduced by the heat exchange with the surrounding coolant and / or fuel by the coolant temperature or fuel. Drives that are already significantly weakened relative to the inlet temperature may not be considered. Preferably, the time period is preset such that, for example, through empirical calculation of the time period that enables the desired compensation of the temperature dependence of the actuator, the operations executed immediately after the length of the time period have a significant effect on the actuator temperature. .

The invention also requires that a higher drive voltage is required to inject the desired amount of fuel as the fuel pressure in the fuel injector, for example in the hydraulic coupler of the fuel injector, is reduced by a number of other actions, ie, continuous, continuous operation. Allow action to be compensated. Since both the heating of the actuator by a plurality of drives and the pressure drop in the fuel injector by the repeated drive are processes having a time-limited action, simultaneous compensation of the two effects is possible. To this end, the time period can be preset, for example, so as to achieve optimal compensation of the two effects as a whole.

In another aspect the invention provides a computer program product for carrying out the method and a control device for driving a fuel injector of an internal combustion engine. The control device includes a time determiner for determining the driving time of the fuel injector, a counter for determining the number of driving of the fuel injector within a preset time interval before the driving time, and a voltage for determining the driving voltage of the fuel injector based on the determined number of times. It includes a determinant.

According to one preferred refinement of the method according to the invention, the determination of the driving voltage and the determination of the number of (drives) at the interrupt point which lies in the vicinity of the pre-settable interrupt period before the driving point are carried out. In this way, the drives carried out immediately before the drive to be executed can also be considered for the determination of the drive voltage, along with the compensation of the effects of very short-term physical processes, such as temperature fluctuations or pressure reduction, preferably.

According to one preferred refinement, the preset time interval is shorter than the combustion cycle of the internal combustion engine. In this case, the drives executed in the preceding combustion cycle, and in which the short-time action of the actuator temperature and / or the pressure in the actuator are significantly weakened, are not considered in the determination of the drive voltage, which has the advantage of very high compensation quality.

According to one preferred refinement, the determination of the number of (drive) times comprises the steps of providing a timer for a pre-settable time interval, increasing the counter value for counting the number of drives, and whether the timer has started. Starting the timer if the timer has not started, detecting whether a preset time interval has elapsed since the timer started, and resetting the counter if the preset time interval has elapsed. It includes. This allows a very simple implementation that can be executed completely, especially in the calculation routine initialized by the interrupt signal just before the drive to be executed.

According to one preferred refinement, the determination of the drive voltage comprises determining a drive voltage default value, determining a correction factor or addition offset based on the determined (drive) number of times, and determining the correction coefficient or addition offset based on the drive voltage default value. Applying to. In this way, the drive voltage can be determined again on the basis of the drive voltage default value within the new time interval after the elapse of the preset time interval, so that an error occurring in, for example, a correction coefficient or an addition offset is not propagated.

According to one preferred refinement, the drive voltage default value is determined based on the coolant temperature or the fuel temperature of the internal combustion engine. This means that the temperature rise of the actuator caused by the actuations is normally normal where the actuator temperature is equal to, for example, the coolant temperature or the fuel temperature, or can be derived by the addition of a constant offset from, for example, one or both of the coolant temperature and the fuel temperature. It is very desirable in that it weakens in a manner approaching the stationary temperature.

In one preferred refinement of the control device according to the invention, the counter state correction value also determines a counter state correction value for applying to the drive voltage default value based on the drive voltage default determiner for determining the drive voltage default value and the counter state of the counter. A determinant is provided. Preferably the control device further comprises a temperature correction value determiner which determines a temperature correction value for application to the drive voltage default value based on the coolant temperature and / or the fuel temperature of the internal combustion engine.

The invention is explained in more detail below on the basis of the embodiments presented in schematic drawings.

1 is a block diagram of a control device for a fuel injector of an internal combustion engine according to an embodiment of the present invention.
2 is a flow chart of a method for driving a fuel injector according to one embodiment.
The same reference numbers in the drawings represent the same elements or elements with the same functions unless otherwise specified.

1 shows a schematic block diagram of a control device 102 of a fuel injection device 160 for injecting fuel into combustion chambers of an automobile internal combustion engine, not shown. The fuel injector 160 is connected by a respective fuel injector 100, for example, connected to a pressure accumulator not shown via the fuel inlet line 154 and to a fuel tank not shown via the fuel return line 152. Is implemented. The actuator included in the fuel injector 100 is connected to the drive unit 158 of the control device 102 via the drive line 150.

The control device 102 includes a drive voltage default determiner 112 that determines the drive voltage default and provides it to its output. The drive voltage default is preferably, for example, to cause the fuel injector 100 to inject the required amount of fuel at a coolant temperature and / or fuel inlet temperature set as standard, and at a compensated temperature ratio between the coolant or fuel and the fuel injector 100. The voltage value used to drive. The drive voltage default value provided by the drive voltage default determiner 112 is applied to the first input of the first multiplier 162 of the control device 102.

The control device 102 determines the temperature correction value based on actual measurements of the coolant temperature and / or the fuel inlet temperature, for example detected by sensors not shown in the internal combustion engine, based on the characteristic curve 170 stored therein. And a temperature correction value determiner 116 to determine. The temperature correction value determiner 116 provides the temperature correction value to the second input of the first multiplier 162. The first multiplier 162 provides the first input of the second multiplier 164 of the control device 102 with the product of the drive voltage default applied to its inputs and the temperature correction value.

The control device 102 includes a counter 106 and a counter state correction value determiner 114, the counter state correction value determiner based on the counter state of the counter 106 based on the characteristic map 172 stored therein. Determine the counter state correction value. The counter state correction value determiner 114 provides the counter state correction value to the second input of the second multiplier 164. The second multiplier 164 provides the voltage determiner 108 of the control device 102 with the product of the counter state correction value applied to its inputs, the temperature correction value and the drive voltage default value. The voltage determiner 108 is configured to determine and provide the actual actuator drive voltage for driving the fuel injector 100 corresponding to the output signal of the second multiplier 164 to the drive unit 158.

The control device 102 also includes a sequential controller 166 that determines the timing of fuel injection to be executed according to the current operating state of the internal combustion engine, the demands of the vehicle driver of the vehicle in which the internal combustion engine is installed, the ambient conditions, and the like. For this purpose, the sequential controller 166 includes a viewpoint determiner 104. The sequential controller 166 is connected to the drive unit 158, thereby instructing the drive unit 158 to transmit a drive signal to the fuel injector 100 for execution of fuel injection at the determined time point. In addition, the sequential controller 166 is connected to the counter 106, thereby sending an indication of the increase and reset of the counter 106 value to the counter. In addition, the sequential controller 166 is connected with a timer 110 provided in the control device 102, thereby indicating an indication of the start of the timer 110 and preset by the timer 110 after the start of the timer 110. A query is sent to the timer as to whether the time interval has elapsed.

2 shows a flow diagram of a method for driving a fuel injector, such as the fuel injector 100 shown in FIG. 1, for example using the control device shown in FIG. 1.

In step 200 a timer is provided for a preset time interval. For example, the timer may be provided as a hardware component or a software component of the control device, wherein the time interval may be stored hard-wired or measured dynamically in an appropriate manner.

In step 201, the timing of driving the fuel injector is determined, for example, based on the current operating state of the internal combustion engine and the crankshaft angle, the vehicle driver's request and / or ambient conditions (eg ambient temperature). In step 203, an interrupt signal is generated that triggers subsequent steps 208 through 221, for example, at an interrupt time that lies near a predetermined interrupt period before the drive time determined in step 201. For example, an interrupt signal of about 450 Hz is sent out before the electronic drive of the timer-coprocessor or the like starts.

In decision step 210, it is checked whether or not the timer provided in step 200 has been started, for example by a processor induced to execute a program by means of the interrupt signal in step 203. If it is determined that the timer has not been started, the process branches to step 212, where the timer is started and the counter provided to count the number of times the fuel injector is driven is set to " 0 ". Then, as the counter value is increased in step 208, the counter now has a counter state "1". If at step 210 it is determined that the timer has already started, the process immediately branches to step 208 where a counter value increment is executed.

In decision step 214, a query of the timer is checked whether the preset time interval (or otherwise) has elapsed since the last start of the timer. If so, the process branches to step 213 where the timer stops, followed by a counter set to the value "1" in step 215. If the preset time interval has not elapsed, steps 213 and 215 are omitted. That is, the counter value increments only while the preset time interval has not yet elapsed since the timer started.

In step 218, a counter state correction factor is determined based on the current counter state of the counter. For this purpose, for example, a pre-settable characteristic curve or characteristic map can be used and other variables, such as the pressure in the fuel pressure accumulator to which the fuel injector is connected, in addition to the counter state can be calculated according to the characteristic curve or characteristic map. . In step 219, a temperature correction factor is determined based on the coolant temperature and / or the fuel inlet temperature of the internal combustion engine. For this purpose, for example, a pre-settable characteristic curve and / or characteristic map may be used, in which other variables, such as the pressure in the fuel pressure accumulator, for example, besides the coolant temperature or the fuel inlet temperature may be calculated.

In step 216 the drive voltage default value is determined based on, for example, the pressure in the fuel pressure accumulator, fuel temperature, inherent parameters of the fuel injector to be driven, and the like. A constant value may be determined as the drive voltage default. In step 220 the counter state correction factor and the temperature correction factor are now applied to the drive voltage defaults. That is, the product of the three variables is calculated. In an alternative embodiment thereof, the correction coefficients determined in step 218 and / or step 219 may be replaced with addition correction values, and corresponding additions may be performed in step 220 for application.

In step 221, the fuel injector is driven using the drive voltage calculated and corrected in step 220 at the driving time determined in step 201. The process then returns to step 201, where a new drive time for a new fuel injection is determined.

Claims (10)

Method for driving (206) the fuel injector 100 of the internal combustion engine,
Determining a driving time of the fuel injector 100 (201);
Determining the number of driving of the fuel injector 100 within a preset time interval before the driving time (200, 208, 210, 212, 214, 215),
Determining (204) a drive voltage of the fuel injector (100) based on the determined number of times. The fuel injector driving method according to claim 1, wherein the determination of the driving voltage (204) and the determination of the number of (drives) at an interrupt time point placed near a preset interrupt period before the driving time point are performed. The method of claim 1 or 2, wherein the preset time interval is shorter than the combustion cycle of the internal combustion engine. 4. A method according to any one of claims 1 to 3, wherein the determination of the number of (drive) times 202 is provided with a step (200) in which a timer (110) is provided for a pre-settable time interval, A step 208 in which the value of the counter 106 is increased, a step 210 of detecting whether the timer 110 is started, and a start of the timer 110 when the timer 110 is not started ( 212, detecting 214 whether a preset time interval has elapsed since the timer 110 started, and resetting the counter 106 if the preset time interval has elapsed 215. And a fuel injector driving method. The method of any one of claims 1 to 4, wherein the determination of the drive voltage comprises determining 216 the drive voltage default value and determining a correction factor or an addition offset based on the determined (drive) number of times (218). And applying (220) the correction factor or addition offset to a drive voltage default value. 6. The method of claim 5, wherein the determination (216) of the drive voltage default value is performed based on coolant temperature or fuel temperature of the internal combustion engine. A storage medium storing a computer program suitable for carrying out the method according to any one of claims 1 to 6 when loaded into an injector inspection device or control device (102) of an internal combustion engine. The control device 102 for driving the fuel injector 100 of the internal combustion engine,
A time determiner 104 for determining a driving time of the fuel injector 100,
A counter 106 for determining the number of driving of the fuel injector 100 within a preset time interval before the driving time point;
And a voltage determiner (108) for determining a drive voltage of the fuel injector (100) based on the determined number of times. 10. The apparatus of claim 8, wherein the drive voltage default determiner 112 determines the drive voltage default value, and the counter state correction value determiner determines a counter state correction value for applying to the drive voltage default value based on the counter state of the counter 106. Control device (102) for driving a fuel injector (114). 10. The method of claim 9, further comprising a temperature correction value determiner 116 that determines a temperature correction value for applying to the drive voltage default value based on the coolant temperature and / or the fuel temperature of the internal combustion engine. Control device 102.

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